TUN-6666: Define packet package

This package defines IP and ICMP packet, decoders, encoder and flow

vendor/github.com/google/gopacket/layers/erspan2.go

@@ -0,0 +1,86 @@
+// Copyright 2018 Google, Inc. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the LICENSE file in the root of the source
+// tree.
+
+package layers
+
+import (
+	"encoding/binary"
+
+	"github.com/google/gopacket"
+)
+
+const (
+	//ERSPANIIVersionObsolete - The obsolete value for the version field
+	ERSPANIIVersionObsolete = 0x0
+	// ERSPANIIVersion - The current value for the version field
+	ERSPANIIVersion = 0x1
+)
+
+// ERSPANII contains all of the fields found in an ERSPAN Type II header
+// https://tools.ietf.org/html/draft-foschiano-erspan-03
+type ERSPANII struct {
+	BaseLayer
+	IsTruncated                         bool
+	Version, CoS, TrunkEncap            uint8
+	VLANIdentifier, SessionID, Reserved uint16
+	Index                               uint32
+}
+
+func (erspan2 *ERSPANII) LayerType() gopacket.LayerType { return LayerTypeERSPANII }
+
+// DecodeFromBytes decodes the given bytes into this layer.
+func (erspan2 *ERSPANII) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
+	erspan2Length := 8
+	erspan2.Version = data[0] & 0xF0 >> 4
+	erspan2.VLANIdentifier = binary.BigEndian.Uint16(data[:2]) & 0x0FFF
+	erspan2.CoS = data[2] & 0xE0 >> 5
+	erspan2.TrunkEncap = data[2] & 0x18 >> 3
+	erspan2.IsTruncated = data[2]&0x4>>2 != 0
+	erspan2.SessionID = binary.BigEndian.Uint16(data[2:4]) & 0x03FF
+	erspan2.Reserved = binary.BigEndian.Uint16(data[4:6]) & 0xFFF0 >> 4
+	erspan2.Index = binary.BigEndian.Uint32(data[4:8]) & 0x000FFFFF
+	erspan2.Contents = data[:erspan2Length]
+	erspan2.Payload = data[erspan2Length:]
+	return nil
+}
+
+// SerializeTo writes the serialized form of this layer into the
+// SerializationBuffer, implementing gopacket.SerializableLayer.
+// See the docs for gopacket.SerializableLayer for more info.
+func (erspan2 *ERSPANII) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error {
+	bytes, err := b.PrependBytes(8)
+	if err != nil {
+		return err
+	}
+
+	twoByteInt := uint16(erspan2.Version&0xF)<<12 | erspan2.VLANIdentifier&0x0FFF
+	binary.BigEndian.PutUint16(bytes, twoByteInt)
+
+	twoByteInt = uint16(erspan2.CoS&0x7)<<13 | uint16(erspan2.TrunkEncap&0x3)<<11 | erspan2.SessionID&0x03FF
+	if erspan2.IsTruncated {
+		twoByteInt |= 0x400
+	}
+	binary.BigEndian.PutUint16(bytes[2:], twoByteInt)
+
+	fourByteInt := uint32(erspan2.Reserved&0x0FFF)<<20 | erspan2.Index&0x000FFFFF
+	binary.BigEndian.PutUint32(bytes[4:], fourByteInt)
+	return nil
+}
+
+// CanDecode returns the set of layer types that this DecodingLayer can decode.
+func (erspan2 *ERSPANII) CanDecode() gopacket.LayerClass {
+	return LayerTypeERSPANII
+}
+
+// NextLayerType returns the layer type contained by this DecodingLayer.
+func (erspan2 *ERSPANII) NextLayerType() gopacket.LayerType {
+	return LayerTypeEthernet
+}
+
+func decodeERSPANII(data []byte, p gopacket.PacketBuilder) error {
+	erspan2 := &ERSPANII{}
+	return decodingLayerDecoder(erspan2, data, p)
+}